The present invention relates to valves used, for example, in aircraft control systems and can find application in any hydraulic system which transforms an output element displacement into a fluid flow driving a hydraulic actuator.
Nowadays, with the advent of supersonic airliners, an urgent problem lies in standardization as a means for improving reliability, extending the service life and attaining pressure-tightness at low inlet pressures of the elements used in aircraft control systems.
The prototype of the proposed invention is the valve incorporated in "Electrohydraulic two-stage digital- control drive" covered by inventor's Certificate No.217,844, USSR.
Considerable disadvantages of such an electrohydraulic valve as well as of the valves utilized in control mechanisms of the type "Hydraulic servocylinder", Series 7, manufactured by Minneapolis Honeywell Regulator Co. (USA) lie in that they are single-functional within the limits of one design, i.e., it is impossible to make a "normally-closed" or a "normally-open" valve without modifying the design of the electromagnet and hydraulic parts of the valve; in low reliability, insufficient service life span, impossibility of ensuring pressure-tightness at low inlet pressures in the "Electrohydraulic two-stage digital-control drive" because of absence of fixed contact between the moving elements of the electrohydraulic valve which increases considerably the impact loads on the stationary parts so that they work under the conditions of an anvil whereas in the above-mentioned valve of American production these disadvantages are caused by the provision of a moving seal.